This invention relates generally to apparatuses for locating punctures or leaks in tires and more particularly, it relates to an apparatus for locating punctures in tubeless tires wherein there are provided a pressure regulator for controlling the pressure on a power device and counterweights for facilitating the lifting of a spider connected to a piston rod in the power device.
In the prior art puncture locaters of the type utilizing a cylinder and piston, a spider is connected to a piston rod fixed to the piston and is actuated by the cylinder for pushing a tire below the level of water in a tank. For the purposes of completeness, reference is being made to our prior U.S. Pat. No. 2,902,856 assigned to the same assignee, wherein a puncture locater having a cylinder containing a piston connected to a piston rod for actuating a spider is described and illustrated with application to tubeless tires.
In such prior art devices, the cylinder and piston assembly is energized by a control button for urging the spider downwardly against the top of the tire in order to force the entire tire beneath the level of the water in the tank. Dependent upon the size and weight of the large tires used on wheels such as that of trucks and trailers, the amount of force or pressure necessary to immerse them in the water would vary. However, there was no provision for controlling or setting the amount of pressure needed by the cylinder to immerse the tires. Thus, an operator had only to guess by looking at the tire to determine what amount of pressure would be required. Frequently, when too much pressure was applied on the smaller tires, the water in the tank would be splashed out onto the working areas or floor. Other times, when the pressure was not enough for submerging the larger tires, the operator had to slowly apply increased amounts of pressure onto the tire until it was completely submerged which is a very time consuming process. It would, therefore, be desirable to provide a pressure regulator operatively connected to the cylinder and piston assembly for controlling and setting the amounts of pressure as required by the size and weight of the tires.
Further, after the punctures or leaks in the tires are located the cylinder and piston assembly is de-energized for permitting the spider to return to its raised position thereby allowing the tire to be removed. However, difficulties have been encountered in the prior art devices in providing enough force for lifting or raising the spider and piston rod up to the raised position after the tire has been checked. Particularly, this problem is present in the checking of the smaller sized vehicle tires as the buoyancy force generated by the tire once the cylinder and piston assembly is de-energized is generally insufficient to overcome the weight of the piston, piston rod and spider in order to raise the same back to the upward position. Thus, it would be desirable to provide counterweights operatively connected to the piston rod so that when the cylinder and piston assembly is de-energized the piston, piston rod and spider are raised in a smooth and efficient manner thereby returning the same to the upright position.